Multi-lumen manometry catheters

ABSTRACT

A manometry apparatus includes a multi-lumen catheter comprising an extruded flexible tube having a plurality of lumens extending through the body of the tube between a proximal end and a distal end. The flexible tube has a first diameter in a proximal portion extending over a part of its length at the proximal end and a second diameter, larger than the first diameter, in a distal portion extending over a part of its length at the distal end. A plurality of flexible connection tubes are each coupled to a respective one of the plurality of lumens by insertion of the respective flexible connection tube into a corresponding lumen. Connection of the multi-lumen catheter to multiple flexible connection tubes is simplified by extruding the distal end of the catheter to a larger dimension so that the connection tubes can be directly inserted into the catheter lumens.

The present invention relates to multi-lumen tubes for use as manometrycatheters, and in particular to improvements in the connectionmechanisms for such catheters.

Various medical diagnosis procedures require the use of manometers thatare capable of measuring pressure simultaneously at multiple locationsalong the length of a tube. For example, in gastrointestinal manometry,a manometry catheter consists of a multi-lumen tube in which eachindividual lumen communicates with a lumen opening, with the multiplelumen openings being located at various points along the length of thetube.

The multi-lumen tube, with its plurality of lumen openings, ispositioned within the tube cavity in which pressure is to be measured,for example, the oesophagus. The lumen openings enable sensing of thepressure in various parts of the oesophagus along its length. Asperistaltic waves from the oesophagus apply pressure to varyingpositions along the tube, these pressures are communicated to pressuretransducers coupled to a distal end of each lumen.

To obtain comprehensive and useful pressure readings from many positionsalong the oesophagus, a corresponding number of lumens must be usedwithin the multi-lumen tube. In a typical example, a nine-lumen tube isused.

A problem encountered is that the multi-lumen tube to be inserted intothe patient's body must of necessity be sufficiently small in diameterso that patient discomfort is minimised, so that undue distortion of theoesophagus is avoided and so that adverse effects on the pressuremeasurement are also minimised.

Although small diameter multi-lumen tubes can readily be formed fromsuitable flexible plastics materials, easy and reliable connection ofeach of the many lumens, at a distal end of the catheter, to separatepressure transducers can be a problem owing to the very small internaldiameter of the individual lumens.

The present invention aims to provide an improved means for coupling theindividual lumens of a multi-lumen catheter tube at a distal end thereofto individual pressure transducer couplings.

According to one aspect, the present invention provides a manometrycatheter comprising an extruded flexible tube haying a plurality oflumens extending through the body of the tube between a proximal end anda distal end, the flexible tube having a first diameter in a proximalportion extending over a part of its length at the proximal end and asecond diameter, larger than the first diameter, in a distal portionextending over a part of its length at the distal end.

According to another aspect, the present invention provides a manometryapparatus comprising:

-   -   a multi-lumen catheter comprising an extruded flexible tube        having a plurality of lumens extending through the body of the        tube between a proximal end and a distal end, the flexible tube        having a first diameter in a proximal portion extending over a        part of its length at the proximal end and a second diameter,        larger than the first diameter, in a distal portion extending        over a part of its length at the distal end; and    -   a plurality of flexible connection tubes each being coupled to a        respective one of the plurality of lumens by insertion of the        respective flexible connection tube into a corresponding lumen.

Embodiments of the present invention will now be described by way ofexample and with reference to the accompanying drawings in which:

FIG. 1 a is a cross-sectional end view of a nine-lumen manometrycatheter of the prior art;

FIG. 1 b is a schematic side cross-sectional view of a manometrycatheter apparatus including connecting device according to the priorart, with the catheter shown in cross section on A-A;

FIG. 1 c is a schematic close up side cross-sectional view of theconnecting device of FIG. 1 b;

FIG. 2 a is a schematic side view of a manometry catheter apparatusaccording to one embodiment of the present invention;

FIG. 2 b is a cross-sectional end view of the distal end of the catheterin FIG. 2 a; and

FIG. 2 c is a cross-sectional end view of the proximal end of thecatheter of FIG. 2 a.

With reference to FIG. 1 a, a conventional multi-lumen tube catheter 1has a diameter of approximately of 5 mm. The catheter has eightperipheral lumens 2 and one central lumen 3 each having an internaldiameter of approximately 1 mm. The catheter is conventionally extrudedin a flexible material such as PVC, using known extrusion processes.

With reference to FIG. 1 b, a conventional manometry apparatus includesa multi-lumen catheter 1 extending from a proximal end 4 to a distal end5. The apparatus further includes a plurality of flexible connectiontubes 6 each connected at a first end to the distal end 5 of themulti-lumen catheter 1 and coupled at the second end to a plug 7. Eachplug 7 is adapted to be received by, and form an airtight seal with, apressure sensing device.

At the proximal end 4 of the catheter 1 an inflation device, such asballoon 8 is coupled to the multi-lumen catheter 1 by way of a frictionfit and/or adhesive or other suitable means. The balloon may be inflatedby way of the central lumen 3, coupled to one of the flexible connectiontubes 6 and corresponding plug 7.

To fulfil the objective of simultaneous pressure measurement at multiplepositions along the length of the catheter 1, each peripheral lumen 2communicates with a lumen opening 9 comprising an aperture in the outerwall of the multi-lumen tube 1. Adjacent to the lumen opening 9, andbetween the lumen opening and the proximal end of the catheter 1 theremaining portion of the lumen 2 is occluded by an occlusion 10 toprevent communication with the proximal end of the catheter 1. Theocclusion 10 may be any suitable device or substance adequate to form anairtight seal within the lumen, such as a pin inserted into the proximalend 4 and glued into place.

With reference to FIG. 1 c, to couple the catheter 1 to the flexibleconnection tubes 6 a plurality of hollow cylindrical pins 11 are engagedin each lumen 2, 3 of the multi-lumen catheter 1, and correspondinglyinto the lumen 12 of a respective flexible connection tube 6. Typically,the hollow cylindrical pins 11 are formed of stainless steel and areglued into place.

It will be noted that the connection of nine stainless steel pins 11 inbetween the multi-lumen catheter 1 and the plurality of flexibleconnection tubes 6 incurs manufacturing costs and assembly costs inproducing such fine, high quality metal components and installing themaccordingly.

It will also be noted that the hollow cylindrical pins 11 also impose areduced internal diameter on the lumen communication between thecatheter 1 and the flexible connection tubes 6. Of necessity, theinternal diameter of the hollow cylindrical pins 11 must be less thanthat of either the catheter lumens 2, 3 or the lumen 12 of the flexibleconnection tubes 6. This is disadvantageous for a number of reasons.

Firstly, it effectively imposes a lower limit on the internal diameterof the lumens being connected, according to the availability of smalldiameter hollow cylindrical pins. This limits the number of lumens thatcan be provided within a catheter of an external diameter dictated bythe medical conditions in which it is to be used.

Secondly, the reduced internal diameter of the hollow cylindrical pinshas adverse effects on the fluid flow through the combinedlumen/connector system. If insufficient fluid flow is achieved throughthe limited internal diameter of the hollow cylindrical pins, this hasan adverse effect on the accuracy and resolution of pressuremeasurements taken therethrough. Similarly, if the internal diameter ofthe hollow cylindrical pins becomes too small, capillary action canstart to have adverse effects on the fluid flows upon which pressuremeasurements are based, resulting in inaccuracies in the measurements.

It will be shown that the present invention avoids the use of the hollowcylindrical pins 11 to connect the multi-lumen catheter 1 to theflexible connection tubes 6.

With reference to FIG. 2 a, a manometry apparatus 100 according to apresently preferred embodiment of the invention includes a multi-lumencatheter 101 which has a proximal end 104 and a distal end 105respectively seen in cross-section in FIGS. 2 c and 2 b. The proximalend 104 comprises a proximal portion 115 that has a first diameter. Thedistal end 105 comprises a distal portion 116 that has a second diameterthat is larger than the first diameter.

Preferably, the proximal portion 115 extends over most of the length ofthe catheter, eg. all excepting about 2 to 7.5 cm, or more preferably,about 2 to 5 cm at the distal end 105 Preferably, the distal portion 116extends over a short length of the catheter, eg. between 1 or 2 and 10cm, or more preferably between 1 and 5 cm, or between 2 and 5 cm.Preferably, the external diameter of the proximal portion 115 isapproximately 5 mm and the external diameter of the distal portion 116is approximately 8 mm.

In the preferred embodiment, the catheter 101 has eight peripherallumens 102 and one central lumen 103. Preferably, the peripheral lumens102 each have an internal diameter in the proximal portion 115 ofbetween 0.4 mm and 1 mm, and an internal diameter in the distal portionof approximately 2 mm. In one arrangement, the central lumen 103 isconveniently slightly larger, eg. between 0.7 mm and 1.5 mm internaldiameter in the proximal portion 104 and approximately 2.5 mm internaldiameter in the distal portion 105.

Currently preferred sizes (diameters) of nine-lumen catheter requiredfor various medical applications are as shown in the table below: LUMENINTERNAL

OUTSIDE

PROXIMAL END DISTAL END PROXIMAL DISTAL PERIPH- PERIPH- TYPE END ENDCENTRAL ERAL CENTRAL ERAL A 4.9 mm 7.9 mm  1.5 mm 0.85 mm 2.5 mm 2.0 mmB 3.9 mm 7.9 mm  1.2 mm  0.6 mm 2.5 mm 2.0 mm C 2.3 mm 7.9 mm 0.74 mm0.46 mm 2.5 mm 2.0 mm

The catheter is preferably extruded in a flexible material such as PVC,polyurethane or any suitable medical grade thermoplastic polymeraccording to known extrusion processes.

In the present invention, it has been recognised that conventionalextrusion process techniques can cheaply and easily be deployed toincrease the diameter of the catheter 101 by slowing up the extrusionprocess for the final few centimetres of the catheter, resulting in atapering outward, then final larger, diameter of catheter. It is alsopossible, during the extrusion process, to apply an increased airpressure in the lumens of the tube being extruded, to control theincrease in diameter of the catheter and its lumens.

In general, both the lateral separation of the individual lumens and theinternal diameter of the individual lumens increase between the proximalportion 115 and the distal portion 116. Preferably, this increase occursin a taper zone 117 resulting from a gradual change in the extrusionprocess.

The manometry apparatus 100 includes the multi-lumen catheter 101together with a plurality of flexible connection tubes 106 eachconnected at a first end to the distal end 105 of the multi-lumencatheter 101 and coupled at the second end to a plug 107. Each plug 107is adapted to be received by, and form an airtight seal with, a pressuresensing device (not shown).

For certain medical applications, such as use of catheters forano-rectal measurements, an inflation device, such as balloon 108 may becoupled to the proximal end 104 of the multi-lumen catheter 101 by wayof a friction fit and/or adhesive or other suitable means. The balloonmay be inflated by way of the central lumen 103, coupled to one of theflexible connection tubes 106 and corresponding plug 107.

Each peripheral lumen 102 communicates with a lumen opening 109comprising an aperture in the outer wall of the multi-lumen tube 101.Adjacent to each lumen opening 109, and between the lumen opening andthe proximal end of the catheter 101, the remaining portion of the lumen102 is occluded by an occlusion 110 to prevent communication with theproximal end of the catheter. The occlusion 110 may be any suitabledevice or substance adequate to form an airtight seal within the lumen,such as a pin inserted into the proximal end 104 and glued into place.Alternatively, the occlusion 110 may be formed by injected glue orresin.

The invention provides for simpler and more efficient coupling of themulti-lumen catheter 101 to the flexible connection tubes 106. Becausethe distal portion 116 of the multi-lumen catheter is expanded duringthe extrusion process, direct coupling of each of the flexibleconnection tubes 106 into a corresponding lumen 102, 103 of themulti-lumen catheter 101 is possible. A simple friction fit between theoverlapping lumen 102, 103 walls and tube 106 walls in a connection zone120 may be used, or more preferably, an adhesive may be used.

It will be noted that the direct insertion of flexible connection tubes106 into the lumens of the multi-lumen catheter 101 ensures that thesmallest lumen diameter encountered between the lumen openings 109 andthe pressure sensor plugs 107 is the internal diameter of the flexibleconnection tubes 106. There is no intermediate restriction of anyconnecting pins 11.

It will also be noted that the manufacturing costs of fine, high qualitymetal components 11 and the associated assembly costs for installingthem are accordingly avoided.

Although the invention has been described and illustrated in the contextof a nine-lumen manometry apparatus, it will be understood that theprinciple applies to other numbers of lumens in a multi-lumen catheter.

Other embodiments are within the scope of the appended claims.

1. (original) a manometry catheter comprising an extruded flexible tubehaving a plurality of lumens extending through the body of the tubebetween a proximal end and a distal end, the flexible tube having afirst diameter in a proximal portion extending over a part of its lengthat the proximal end and a second diameter, larger than the firstdiameter, in a distal portion extending over a part of its length at thedistal end.
 2. The manometry catheter of claim 1 in which the proximalportion extends for a substantial part of the length of the catheter andthe distal portion extends for a relatively small part of the length ofthe catheter.
 3. The manometry catheter of claim 2 in which the distalportion has a length in the range 1 to 10 cm.
 4. The manometry catheterof claim 2 in which the distal portion has a length in the range 1 to 5cm.
 5. The manometry catheter of claim 1 in which the lateral separationof the individual lumens within the flexible tube is increased withinthe distal portion.
 6. The manometry catheter of claim 1 in which theinternal diameter of the individual lumens within the flexible tube isincreased within the distal portion.
 7. The manometry catheter of claim1 in which the outside diameter of the proximal portion lies in therange approximately 2 mm to 5 mm and the outside diameter of the distalportion is approximately 8 mm.
 8. The manometry catheter of claim 1 inwhich the inside diameter of lumens located adjacent the periphery ofthe catheter lies in the range approximately 0.74 mm to 1.5 mm in theproximal portion and approximately 2 mm in the distal portion.
 9. Themanometry catheter claim 1 further including a lumen openingcommunicating with each of a plurality of said lumens extending throughthe catheter walls to an outer surface thereof.
 10. The manometrycatheter of claim 9 in which each lumen opening is located at adifferent longitudinal position along the catheter.
 11. The manometrycatheter of claim 1 in which the distal portion includes a taperedregion between the distal end and the proximal portion.
 12. A manometryapparatus comprising: a multi-lumen catheter comprising an extrudedflexible tube having a plurality of lumens extending through the body ofthe tube between a proximal end and a distal end, the flexible tubehaving a first diameter in a proximal portion extending over a part ofits length at the proximal end and a second diameter, larger than thefirst diameter, in a distal portion extending over a part of its lengthat the distal end; a plurality of flexible connection tubes each beingcoupled to a respective one of the plurality of lumens by insertion ofthe respective flexible connection tube into a corresponding lumen.